1. Field of the Invention
The present invention relates to a storage subsystem and a storage controller, both connected to host computers. More particularly, the invention relates to a storage subsystem and a storage controller adapted to provide enhanced performance and reliability.
2. Description of the Related Art
In recent years, storage controllers have been required to provide better performance, higher reliability and greater availability than ever before as computer systems are getting larger in scale to process data at higher speeds than ever before, 24 hours a day and 365 days a year, with data transfer interfaces also enhanced in speed. Illustratively, Japanese Patent Laid-open No. Hei 11-7359 discloses a storage controller incorporating an internal network to improve its performance.
There has been a growing need for connecting a storage controller to a plurality of host computers having multiple interfaces, as shown in FIG.8. In such a storage controller, a host interface section comprises a host interface for addressing each different host computer. A control processor in each host interface analyzes I/O commands received from the corresponding host computer and exchanges data accordingly with a cache memory 215 over a signal line. Japanese Patent Laid-open No. Hei 9-325905 illustratively discloses one such storage controller.
Techniques have been known recently which substitute a fibre channel interface for the SCSI (Small Computer System Interface) between a host computer and a storage controller. Illustratively, Japanese Patent Laid-open No. Hei 10-333839 discloses techniques for connecting a storage controller with a host computer using a fibre channel interface. The disclosed storage controller is designed for dedicated use with a host computer having a fibre channel interface.